Studying Bacterial Pathogenesis: Approaches and Methods Flashcards
Why is it important to study bacterial pathogenesis?
To improve prevention, diagnosis and treatment of bacterial disease
How can bacteria disease be prevented?
Vaccines
How can bacterial disease be diagnosed?
Toxin detection
How can bacterial disease be treated?
Identifying new therapy targets
What is bacterial pathogenicity?
The ability of a bacterium to inflict damage on the host
What does bacterial pathogenesis involve?
Bacterial and host factors
Give examples of bacterial factors
Virulence factors
Toxins
Immune evasion
Attachment
Motility
Gene regulation
Spread
Resistance
Give examples of host factors
Immune response
Skin
Phagocytes
Complement
Fe restriction
Abs
Lymphocytes
Macrophages
How can we prove that a bacterium is responsible for a particular disease?
Using Koch’s postulates:
1. Bacterium is found in all people with the disease
2. The bacterium can be isolated from patients and maintained in pure culture
3. The pure culture can be inoculated into a human volunteer or animal model and cause symptoms of the disease
4. The bacterium can be re-isolated from the volunteer or animal
e.g. Helicobacter pylori
What is needed to investigate bacterial pathogenesis?
Clinical observation and epidemiology
Models of disease - in vivo and in vitro
Appropriate strains of bacteria to test - inc geneticall modified bacteria
What is epidemiology?
Study of spread and distribution of disease
In bacteriology it often includes the discrimination of different strains/variants and their spread
How is clinical observation and epidemiology done?
Identifying the problem
Identifying common features of cases
Determining which tissues are targeted
Identifying if all people are equally susceptible
Identifying how it spreads
Sources of outbreaks
Causative organism
Identifying if all strains are equally pathogenic
How are good epidemiological studies designed?
Clear definitions of patients with and without the disease
Sufficient numbers of patient to investigate - statistical significance
Collection of relevant information and samples
Consider ethics, patients are complex, logistics
What are the different models of disease?
Bacterial behaviour in rich or specialised growth media (in vitro)
Bacterial behaviour in laboratory conditions (in vitro) that mimic in vivo
Animal models (in vivo)
Describe behaviour on/in rich or specialised growth media
e.g. agar plates or tryptone soy broth medium (TSB)
